Product streams from acid catalyzed alkylation reactions contain dissolved acid catalyst and small amounts of alkyl esters of the acid catalyst. These compounds have to be removed from the product stream prior to further processing. It is known from DK Patent Application No. 0804/97 to remove (less than 1 ppm) acid compounds and alkyl esters from a hydrocarbon stream by passing the stream through a bed of silicagel wetted with water. The acid can, subsequently, be recovered by washing with water.
Isobutane alkylation is known to be catalyzed by perfluorinated sulphonic acids, including trifluoromethanesulphonic acid (U.S. Pat. No. 5,220,095 and U.S. Pat. No. 5,245,100). Alkyl esters of these acids, e.g. isopropyltriflate (i-PrOTf), are formed as intermediates in the above process and are present in small amounts in the product stream from the alkylation process at typical operation conditions. It is further known to recover triflate esters from the above process by aqueous extraction of the product stream.